The proposed StirScan project will develop a NDT system in order to address the challenging problem of detecting kissing bonds in Friction Stir Welds (FSW). FSW is a relatively new joining technique for aluminium alloys which offers good joint performance and excellent reproducibility – this is of significant interest to the aerospace sector, where fatigue performance is particular crucial. However, “Kissing bonds” are a concern with FSW as such features can reduce fatigue performance of joints and currently are very difficult to detect (or accurately size) using existing NDT methods. This concern limits the adoption of FSW joining in aerospace, particularly for critical components. The StirScan project will develop a new NDT method to enable the detection of kissing bond defects below 0.3mm in length in aerospace components. A novel non-linear ultrasonic technique and an oblique incidence high frequency ultrasonic technique will be used for the assessment. The technique will lead to a more sensitive measurement of interfacial defects and will detect small kissing bond flaws. A scanner with an incorporated probe holder will be designed and manufactured that will enable rapid inspection of FSW. The developed NDT inspection system will allow assessment of high performance aluminium FSW joint components for aero structures. This work will support the increased adoption of FSW in the aerospace industry.